Field of the Disclosure
The present disclosure relates to a semiconductor technology, and in particular, it relates to a high-voltage semiconductor device having excellent isolation capability.
Description of the Related Art
High-voltage semiconductor technology is applied to integrated circuits (ICs) with high voltages and high power. Traditional high-voltage semiconductor devices, such as double diffused drain MOSFET (DDDMOSFETs) and lateral diffused MOSFET (LDMOSFET) are mainly used for devices with at least 18 volts or higher. The advantages of high-voltage device technology include cost effectiveness and process compatibility, and thus high-voltage device technology has been widely used in display driver IC devices, and power supply devices, and power management, communications, autotronics, and industrial control fields, etc.
Because of the properties of compactness and high output current of the DDDMOSFET, it has been widely used in source driver IC devices with an operating voltage of less than about 30 volts. A double diffused drain (DDD) is formed of two implantation regions that serve as a source or drain in a high-voltage MOSFET device. Herein, the term “high-voltage MOSFET device” refers to a transistor device having a high breakdown voltage.
Adjacent DDDMOSFETs are typically isolated from each other by the use of a filed oxide, such as a trench isolation structure. The trench isolation structure, a metallization layer (e.g., including an inter-layer dielectric (ILD) layer and an interconnect wiring layer) over the trench isolation structure, and a well region under the trench isolation structure form a parasitic MOS transistor. As a result, when the DDDMOSFET is operated, the parasitic MOS transistor would be easily turned on by the voltage applied to the interconnect wiring layer, so that the function of isolation that is provided by the trench isolation structure fails, thereby resulting in a circuit failure. Therefore, the width and/or the depth of the trench isolation structure must be increased to prevent the parasitic MOS transistor from being turned on while the DDDMOSFET is operating.
However, device size increases with increased width and/or depth of the trench isolation structure, thereby resulting in increased chip area. Additionally, processing difficulties and manufacturing costs also increase with the increased depth of the trench isolation structure. Therefore, there is a need to develop a high-voltage semiconductor device and a method for manufacturing the same that are capable of addressing the problems described above.